The increase in the serum cholesterol level of the rabbit fed a high cholesterol diet was prevented by the administration of a Lactobacillus sporogenes preparation, proportionally to the amount of the preparation. About 90% of the increase in the serum cholesterol level was inhibited in the rabbits fed the preparation (2%) as feed additives. In vitro, L. sporogenes cultured in MRS broth containing PPLO serum fraction as a cholesterol source decreased the cholesterol concentration in the spent broth and increased the intracellular cholesterol concentration. The ability of L. sporogenes to accumulate cholesterol was enhanced by the presence of oxgall in the medium. These results suggest that L. sporogenes may directly assimilate the cholesterol in the gastrointestinal tracts and may prevent the increase of the serum cholesterol level.